Wastegate signal
09-13-2008, 05:23 PM
#23
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Yeah, he's like that dude who retired from the FED, Alan Greenspan. Greenspan would say something nobody could understand but that they could all interpret anyway they wanted and billions would be made and lost on the world markets.
In Corky's case, that's just how engineers talk. I think it means, "the info's out there, here's some more, figure out what works for your situation."
In Corky's case, that's just how engineers talk. I think it means, "the info's out there, here's some more, figure out what works for your situation."
Last edited by Thucydides; 09-13-2008 at 05:39 PM.
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09-20-2008, 03:55 PM
#24
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Flogging a dead horse...
Compressor outlet: tightest control, but boost at throttle plate will fall off at high RPM because there is no measurement/compensation for pressure drop across the I/C. Worth considering a way to modestly reduce the effective boost at high RPM as a cap to the maximum stress on the engine.
Plenum: slightly looser (and possibly less stable) boost control, but maintains constant boost at the throttle plate across entire RPM range.
Intake Manifold: Maximum responsiveness when opening the throttle, but lousy on a) throttle linearity and b) heat/efficiency at partial throttle because the compressor output may climb very much higher than the target boost level. Example: a) boost target of 15 psi, b) engine at partial throttle with 3 psi boost in the intake manifold, requires c) 25 psi pressure in the plenum side of the throttle late resulting in d) huge backpressure on the exhaust side of the engine, but e) the still the wastegate remains closed -- trying to build even more boost -- because the WG signal is still 12psi below the boost target.
M.
Compressor outlet: tightest control, but boost at throttle plate will fall off at high RPM because there is no measurement/compensation for pressure drop across the I/C. Worth considering a way to modestly reduce the effective boost at high RPM as a cap to the maximum stress on the engine.
Plenum: slightly looser (and possibly less stable) boost control, but maintains constant boost at the throttle plate across entire RPM range.
Intake Manifold: Maximum responsiveness when opening the throttle, but lousy on a) throttle linearity and b) heat/efficiency at partial throttle because the compressor output may climb very much higher than the target boost level. Example: a) boost target of 15 psi, b) engine at partial throttle with 3 psi boost in the intake manifold, requires c) 25 psi pressure in the plenum side of the throttle late resulting in d) huge backpressure on the exhaust side of the engine, but e) the still the wastegate remains closed -- trying to build even more boost -- because the WG signal is still 12psi below the boost target.
M.
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09-20-2008, 10:03 PM
#25
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Good thread!
Many DSMs tap into the BOV line, which itself is sourced from the intake manifold. I've been running this setup myself for the better part of 6-7 years now. With a ball-spring MBC hooked up in the signal line, is there still a risk to the wastegate actuator canister?
Many DSMs tap into the BOV line, which itself is sourced from the intake manifold. I've been running this setup myself for the better part of 6-7 years now. With a ball-spring MBC hooked up in the signal line, is there still a risk to the wastegate actuator canister?
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09-20-2008, 10:05 PM
#26
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Good thread!
Many DSMs tap into the BOV line, which itself is sourced from the intake manifold. I've been running this setup myself for the better part of 6-7 years now. With a ball-spring MBC hooked up in the signal line, is there still a risk to the wastegate actuator canister?
Many DSMs tap into the BOV line, which itself is sourced from the intake manifold. I've been running this setup myself for the better part of 6-7 years now. With a ball-spring MBC hooked up in the signal line, is there still a risk to the wastegate actuator canister?
The wastegate/mbc should have their own dedicated vacuum source.
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